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  View original topic: Is this voltage adaquate?
DarkMesa8 Sat Jan 22, 2005 2:14 pm

When I was about to install a new alternator, I noticed the previous alternator was not wired properly (no voltage to the idiot light switch). Wired it properly, and it started spitting out voltage!

But, this is a remanufactured alternator close to 8 years old. I only get 13.59 volts at the alternator, and 12.98 volts at the battery (brand new) itself. For a modern car that was just started (cold) this would be pretty low prior to heat soak setting in. My GT runs 14.6 volts right after startup.

Is that voltage low? Should I throw the new alternator in anyways? What voltage do you all get?

TeamSpatula Sat Jan 22, 2005 3:51 pm

How many amps is the alternator rated for? Check that vs the amperage it's putting out...that sounds like a pretty good figure, but that's from talking to others, not my direct experience...

dstefun Sat Jan 22, 2005 7:28 pm

Recheck your battery voltage. With engine not running battery should be at least 12.5 V. If not, charge the battery with a charger. If you can't keep it at 12.5V or above not running, battery has a problem or you have a current drain - check it again with battery disconnected.

At idle it should be 12.5 to 13.5 V. Above idle should go up to 14 to 14.6 V. If you don't have at least 14V above idle then the alternator/regulator/wiring has a problem somewhere. Check all the connections for loose, broken, or corrosion. Anything above 15V means your regulator is not regulating.

You shouldn't have 0.6 volt drop between the alternator output and battery - check all the connections along the way, something is corroded.

Led Zeppelin Sat Jan 22, 2005 7:53 pm

I say your good. My Gen only gives out 10-13v i forget... ill check tomorrow and let u know

dstefun Sat Jan 22, 2005 8:38 pm

Led Zeppelin wrote: I say your good. My Gen only gives out 10-13v i forget... ill check tomorrow and let u know
A good gen should give you 14V at the battery above idle. Maybe even 14.5 but 14 would be good. A good alt should easily give you 14 - 14.7.

Led Zeppelin Sat Jan 22, 2005 9:14 pm

hmm idunno then i should check mine. Mine has never givin me problems though... i can listen for my cd p[layer 5 hours and the batterie wont die

DarkMesa8 Sun Jan 23, 2005 12:04 am

Battery was pretty darn close to 12.5 volts with the car off, it was fresh off the shelf.

I'll clean all terminals to see why there's such a steep difference in voltage between the battery and alternator. It is an alternator, as I was surprised to find out.

Led Zeppelin Sun Jan 23, 2005 9:32 am

What year engine is it? If your not sure (A lot of times engines are replaced with later models... 74 is popular) look at the gen stand and get the first 2 letters and post them here ill tell u.

I say you shouldnt worry about it unless u start having problems. If you worry about possibilities then u will be worrying your whole VW life.

So just drive it and if ur battery dies and ur car wont stay on cause ur alt. isnt working... replace ur alt.

DarkMesa8 Sun Jan 23, 2005 10:46 am

I think this is the path I'll follow. Thanks everyone!

bill may Mon Jan 24, 2005 4:31 am

uh..duh..uh look at casting near studs go on. does it say 14 volts? my generater does.



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